Semiconductor manufacturers have recently been experimenting with metal source/drain MOSFETs. Metal source/drain offers lower sheet resistance than doped silicon, possesses infinite abruptness, and exhibits low contact resistance. In addition, there is no issue with random doping effect from source/drain to the channel. Lower cost due to the elimination of implanters and fancy annealing tools is also a driver.
However, for metal source/drain to work, the Schottky barrier height between the metal and conducting channel in the silicon should be close to zero for acceptable drive current. No such metals or metal silicides currently exist to achieve this. Currently, ErSi and PtSi have the lowest barrier height, but the barrier height is still greater than 0.15 eV, which is too high for metal source/drain.